frequently asked questions

  • Typical question about sheathing

    What adhesive is used for Gypsum Sheathing?

    Any 121 Base Coat & Adhesive, 302, 395 Liquid Membrane Adhesive, and 303 can be used for Gypsum Sheathing.


  • Typical questions about coatings & finishes

    Can parex coating be applied directly to glass mat gypsum sheathing or other approved sheathings?

    Parex coating can be directly applied to a sheltered soffit area. Direct application to Dens-Glass Gold as a primary wall cladding is not approved other than for specific exceptions

    What colors can safely be used over (EPS) insulation board?

    Parex recommends color choices with a light reflctance value of 30% or greater be used on (EPS) insulation board. For darker applications, consult Parex Technical Services for further options.

  • Typical question about primer

    What benefits are there when primer is used?

    Consistent and brighter colors, reduced absorptiveness of the base coat for longer open time to float finishes, provides a sealer over the base coat and reduces the chance of efflorescence bleed through, and improves the coverage of the finish.

    What primer is required to use with Parex Cerastone 630?

    Parex requires using Parex Sanded Primer 313 or Primer 310.

    Is there a color variation if you compare finish over primed vs. unprimed applications?


  • Typical question about expansion joints

    Where should continuous expansion joints be installed?

    Continuous expansion joints shall be installed in the following locations:
    A) At building expansion joints.
    B) At substrate expansion joints.
    C) At floor lines in wood framed construction.
    D) Where the Standard System abut one another.
    E) Where the Standard System abut other materials.
    F) Where significant structural movement occurs, such as:
        1. Changes in roofline.
        2. Changes in building shape and / or structural system.
    G) Where the substrate changes.


    Does Parex require an expansion joint at all floor lines?

    At wood framed buildings only. Unless there is a Web Truss floor joist, wood I-beam Truss-joist type, or Laminated Veneer Lumber floor joist, then there is no expansion joint needed.

    What is the minimum space required for expansion joints?

    Parex recommends a minimum gap of ¾" for expansion joints unless otherwise specified by the architect.

  • Typical question about insulation boards

    What is the minimum thickness of EPS insulation board that can be used for PB EIFS?

    ¾ inch is the minimum thickness of EPS insulation board to be used for a PB EIF system. Parex recommends using at least 1 inch of insulation board

    Can XPS insulation board be adhesively attached?

    Yes. XPS sanded or mechanically rasped insulation board can be adhesively attached with I-C One Base Coat 308, but only to concrete, masonry and stucco surfaces. However, the adhesive attachment must be supplemented by mechanical fasteners, typically 4 per 2' x 8' sheet of XPS.

    What is the minimum thickness of EPS that can be mechanically fastened?

    1-1/2 inches is the minimum thickness of insulation board that can be mechanically attached.

    How big of a gap should be filled after insulation board is attached and what should be used?

    Any gaps in insulation board greater than 3/32" should be filled with slivers of insulation board or Polyurethane Spray Foam. Don't use latex spray foam.

    If EPS insulation board stays in the sun for a long period of time and yellowing occurs what should be done?

    The EPS insulation board should be rasped down until the yellowing is removed. Make sure that there is at least ¾" of insulation board remaining after the rasping is done.

    How do we check for the quality of the EPS in the field?

    To test the EPS board, break a small piece in half and smell immediately. The board should not be used if there is a noticeable solvent odor.

  • Typical questions about Parex systems

    What type of systems does Parex have to offer?

    Standard System, Standard WaterMaster LCR System, Standard WaterMaster System, Optimum System


  • Typical question about mechanical fasteners

    What type of fasteners does Parex require for mechanically fastening insulation board to a substrate?

    Parex recommends using Wind-Lock's Wind-Devil 2 Mechanical Fasteners for EPS and Windlock U.L.P. Plates for XPS.


  • Typical questions on cementitious base coats/adhesives

    What causes efflorescence in cementitious base coats?

    A combination of circumstances causes efflorescence. First, there must be soluble salts in the material. Second, there must be moisture to pick up the soluble salts and carry them to the surface. Third, evaporation or hydrostatic pressure must cause the solution to move. If any one of these conditions is eliminated efflorescence will not occur.


  • Typical questions on sealants

    What kind of sealant does Parex recommend?

    Parex recommends an ultra-low modulus sealant that is capable of 100% elongation and 50% compression.

  • Typical questions on reinforcing mesh

    What are the classifications and impact ranges established for Class PB CI?

    Classification Impact Range
    Standard Impact Resistance 25-49 inch-lbs.
    Medium Impact Resistance 50-89 inch-lbs.
    High Impact Resistance 90-150 inch-lbs.
    Ultra High Impact Resistance 150 inch-lbs.
  • Typical question about terminations

    What are the ways that an CI system can be terminated?

    There are 4 ways to terminate a Parex CI System:1. Backwrapping2. Edge wrapping3. Vented Track4. Seal Tape

    What is back wrapping?

    Backwrapping is the traditional method of encapsulating the insulation board edge. Back wrapping simply means that the insulation board is wrapped in fabric reinforced base coats at edges at terminations and that the mesh extends behind the insulation boards at least 2.5". Edgewrapping means that mesh reinforced base coats extends over the edges of insulation at terminations and onto the framing or masonry.

    What is vented track used for?

    Vented track is used in many locations as an alternative to backwrapping. Although it cannot be used in every situation, it provides a convenient alternative to backwrapping, and is a time saving accessory to applicators.

    How high should the CI system be terminated above grade, pavaement, and rooflines?

    he CI system should be terminated above pavement and above rooflines a minimum of 2 inches. The system should be terminated a minimum of 6 inches above grade at un-paved areas.






Parex Technical Support


[email protected]